Method websocket

dash/_callback_context.py:333–355

Get WebSocket interface if running in WebSocket context. Returns the DashWebsocketCallback instance if the callback is being executed via WebSocket, otherwise returns None. Raises: RuntimeError: If websocket_callbacks is requested but the backend

(self)

    @property
    @has_context
    def websocket(self) -> typing.Optional[DashWebsocketCallback]:
        """Get WebSocket interface if running in WebSocket context.

        Returns the DashWebsocketCallback instance if the callback is being
        executed via WebSocket, otherwise returns None.

        Raises:
            RuntimeError: If websocket_callbacks is requested but the backend
                doesn't support WebSocket.
        """
        ws = _get_from_context("dash_websocket", None)
        if ws is None:
            app = get_app()
            if (
                hasattr(app, "_websocket_callbacks")
                and app._websocket_callbacks  # pylint: disable=protected-access
                and not app.backend.websocket_capability
            ):
                raise RuntimeError(
                    f"WebSocket callbacks requested but backend "
                    f"'{app.backend.server_type}' doesn't support them."
                )
        return ws


callback_context = CallbackContext()